1. Field of the Invention
The present invention relates to an optical burst receiver that adjusts the duty of an output signal. In particular, the present invention relates to an optical burst receiver and method capable of reducing the number of components and manpower in the duty adjustment of an output signal.
2. Description of the Related Art
External components other than the LSI (large scale integration) are attached to an optical burst receiver for manual adjustment in order to stably adjust the duty ratio (Duty) of an output signal without depending on the temperature and the optical input power.
A first problem in such an optical burst receiver is that since external components other than the LSI are required, the area where the external components are to be mounted needs to be large, and the miniaturization of the optical burst receiver is difficult.
A second problem is that much manpower is required for manual adjustment, and the cost of the optical burst receiver is high.
A technique related to the optical burst receiver for duty adjustment is described in Japanese Patent Laid-Open No. 2004-343247.
The technique described in Japanese Patent Laid-Open No. 2004-343247 is for correcting the duty ratio of a received signal to 50% to allow accurate identification and reproduction of an electrical signal in a compact and low-cost system.
An opto-electrical converter/amplifier converts an input optical signal to an electrical signal and transmits the electrical signal to a differential wideband amplifier and a trigger generator. The trigger generator generates a trigger signal and transmits the trigger signal to a duty ratio correction circuit.
The differential wideband amplifier transmits an output signal to an identifier/reproducer, the duty ratio correction circuit, and a clock generator. Based on the output signals of the trigger generator and the differential wideband amplifier, the duty ratio correction circuit generates a control signal for correcting the duty ratio of the output signal of the differential wideband amplifier and transmits the control signal to the differential wideband amplifier.
The clock generator generates a clock signal and transmits the clock signal to the identifier/reproducer. Based on the clock signal, the identifier/reproducer identifies and reproduces the signal transmitted from the differential wideband amplifier.
Control is performed based on the duty in a preamble pattern in the technique described in Japanese Patent Laid-Open No. 2004-343247. However, there is a problem in that the technique is not sufficient for further controlling the duty ratio in which a plurality of pieces of control information are included in the preamble signal.